Tuesday 5 July 2011 18.40 EDT
First published on Tuesday 5 July 2011 18.40 EDT

David Cameron and the attorney general, Dominic Grieve, will come under sustained pressure to hold a public inquiry into phone hacking at the News of the World and the conduct of the police investigation into the practice over the past five years. Ministers are also likely to face calls for a cross-party initiative to examine media regulation.

On a day when it appeared that a dam protecting News International finally burst, senior politicians competed with one another to condemn the company.

Ed Miliband, the Labour leader, called on the News International chief executive, Rebekah Brooks, to consider her position and conscience. He said: "The issue is not simply what she knew, but what happened on her watch."

Ending months of concern that he would be seen to be singling out News International, Miliband said: "It is up to senior executives at the News of the World and News International to start taking responsibility for criminal activities over a sustained period. Every decent British journalist should regard this episode as a stain on their professional integrity and the reputation of their industry.

"I remain instinctively a supporter of self-regulation for the press. But like everyone else in this country I can see that the current system is clearly not working".

It is understood a series of bruising phone calls were held between Labour and News International executives over the credibility of Brooks's position, but Miliband is not yet prepared to draw a link between News of the World phone hacking, and the planned News Corp bid for a majority stake in BSkyB.

In a sign of the anger gripping Westminster, the Speaker, John Bercow, surprised the government by granting an emergency three-hour Commons debate into the issue on Wednesday.

Coalition ministers spent the day in parliament and in TV studios, holding the line that there will be no decision on a public inquiry until the current police investigation has run its course. They also insisted the scandal could have no impact on the imminent ministerial decision on whether to allow News Corp to take over BSkyB.

But Tim Farron, the Liberal Democrat president, said News Corp executives had by their conduct proved themselves not to be "fit and proper persons" to take over BSkyB. He also called for a review into the narrow laws on media plurality, possibly in a new communications bill.

It is known his stance has the private support of cabinet ministers who believe some kind of commission into media ownership and regulation will have to be established.

Farron said: "This is not just about disgust. It is about what we are going to do about it. There will have to be a public inquiry once the police inquiry is over and we should agree to that now.

"But we also have to decide whether these are fit and proper persons to take over BSkyB, and whether their assurances amount to anything. This goes far deeper than one individual, it appears to have been about a culture and a complete lack of ethics.

"We ought to be able to look at whether News International is indeed a fit and proper body to own its current share of the UK media market, let alone a greater one. I ask myself: is Rupert Murdoch a fit and proper person to own any more of the media market – well, certainly not."

The deputy prime minister and Liberal Democrat leader, Nick Clegg, had earlier described the phone hacking as grotesque. Pressed in the Commons by Labour's deputy leader, Harriet Harman, to accede to a public inquiry, Clegg said: "If there are wider issues that need to be looked at once the police investigation is complete, of course we can return to them.

"The key thing – this is what Milly Dowler's family and families up and down the country want to know – is: who did what when, who knew what they were doing and who will be held to account? We will be able to get to the bottom of that only when the police ruthlessly pursue the evidence, wherever it leads."

In Kabul, David Cameron described the revelations as truly shocking, but said he would not intervene in News Corporation's bid to take a majority stake in BSkyB, saying it was a decision for culture secretary Jeremy Hunt alone.

Labour is also looking at the idea of an immediate cross-party initiative to bring trust back into newspaper regulation, effectively a call to reform or disband the current system of press regulation under the Press Complaints Commission. Such a cross-party push would follow Miliband's call for a bipartisan examination of future funding of social care.

In the Commons, the Speaker John Bercow caught the government by surprise when he granted a Labour call for an emergency debate under the rarely used SO24 procedure.

It is the first time a Speaker has granted such a debate since 2008. If the Speaker grants a call for an emergency debate 40 MPs have to stand up and support his decision. Labour flooded the chamber to do so, and were joined by a smattering of Liberal Democrats and Tory backbenchers including Bill Cash and Zac Goldsmith.

Making the case for an emergency debate, Labour MP Chris Bryant said: "This is not just about one incident, hideous as it is, it's about systematic criminality which has perverted police investigations and seriously damaged the reputation of British journalism and the Metropolitan police.

"It is about the pattern of lies and half-truths told to parliament by the News of the World: that there was just one lone reporter, that no senior managers knew anything about all of this. But what makes it really important and urgent is it's about the behaviour of the Metropolitan police in who we put our trust. They had all this information in their hands in 2006 and yet they did nothing with it.

"Why have they lied time and time again to parliament, saying that a full investigation had been done, saying that all the victims had been informed when self-evidently they hadn't been? The only way we can get to the full truth and the heart of the cover-up is to have a public inquiry, led by a judge, in addition to the police investigation."

The Speaker said he was "satisfied that the matter is proper to be debated".